Estimation of disability-free life expectancy and loss of disability-free life expectancy in patients with non-small cell lung cancer

Purpose: To quantify the societal impact of disability in patients with non-small cell lung cancer (NSCLC), this study estimated the disability-free life expectancy (DFLE), loss-of-DFLE and explored their associations with quality-adjusted life expectancy (QALE) and loss-of-QALE. Methods: : We interlinked national databases and applied a rolling-over algorithm to estimate the lifetime survival function for patients with NSCLC. Using the EuroQOL-5 Dimension (EQ-5D) and Barthel index (BI), we repeatedly measured the quality-of-life and disability functions of NSCLC patients who visited our hospital from 2011 to 2020. Age-, sex-matched referents were simulated from lifetables of the same calendar year of diagnosis. We categorized BI scores ≤70 as in need of long-term care and constructed linear mixed models to estimate the utility values and disability scores. Results: : We collected 960 cases and 3088 measurements. The proportions of measurements without disability at age <65 and in stage I-IIIa, age <65 and stage IIIb-IV, age ≥65 and stage I-IIIa and age ≥65 and stage IIIb-IV were 97.3%, 89.3%, 94.8%,78.3%, corresponding to DFLEs of 15.3, 2.4, 6.8, 1.2 years and losses-of-DFLE of 8.1, 20.7, 4.0, 8.6 years, respectively, indicating that advanced stage had a stronger effect than old age. Survivors in advanced stages showed increased demands for assistance in almost all subitems. The DFLEs seemed to be approximate to the QALEs and the latter were shorter than the former due to discomfort and depression. Conclusion: From a societal perspective, future health technology assessment should consider the impact of lifetime duration of functional disability. Early diagnosis of NSCLC may decrease the burden of long-term care.